A road milling machine is a self-propelled machine, of known technology, finalized to the demolition of road pavements by means of milling with rotating milling drum. The road milling machines generally are equipped with fixed width milling drums contained in a housing opened downwardly to ensure the contact of said milling drum with the surface to mill and opened frontally for the flow of the milled material outside of the milling drum housing. To change the milling width it is necessary to replace not only the milling drum, but also a series of equipments dependent from the sizes of the milling drum itself.
Solutions concerning milling drums modifiable with different cutting widths are also known, which solutions however generally involve difficulties in the assembling or modification and long set-up times.
EP0694651 discloses an improvement of a cold road milling machine having means for the advancement of the machine and a milling drum mounted on the machine for cutting a certain material width along the path of the machine and a conveyor mechanism for transporting the milled material generated by the cut of the milling drum away from the machine, the improvement including:                a. a rotating milling drum divided into two or more sections with at least one of said sections being divided into segments.        b. means for the assembly of said segments on said milling drum whereby when said segments are mounted to said milling drum, the width of cut of the milling drum is increased, and when said segments are removed from said milling drum, the width of cut is decreased;        c. a drive train for providing power to rotate said milling drum;        d. said drive train having a power input end and a power output end;        e. a first section of the milling drum being connected at the power output of the transmission train and substantially flush mounted with reference to the drum end opposite to the power input of the entry of power of the drive train, and one or more additional segmented sections.        f. means to connect the segments of said additional sections to said first section of the drum, where said additional segmented sections are mounted between the first section of the drum and the power input of the drive train.        g. a planetary gear device that transmits the power output to the milling drum, a transmission shaft that comes through the milling drum and connected to the planetary gear, milling means surrounding said planetary gear.        
U.S. Pat. No. 5,722,789 discloses an improvement of a cold road milling machine, said machine including a drive train having an end for the intake of the power at one side of the machine and an end for the delivering of the power on the other side of the machine, said intake end of the power of said drive train being connected to a power source. Said delivering end of the power of said drive train connected to a reduction gear mounted within an appropriate housing, said housing of the reduction gear having opposite ends, an end of said housing of the reduction gear being generally flush mounted on the side of the machine corresponding to the power delivering side, said housing of the reduction gear being mounted for the rotation, in relation to said machine, of a cylinder that extends from the opposite end of said housing of the reduction gear towards the other side of said machine, means to command the rotation of said cylinder, said improvement including:                a. a set of milling drums, each drum in said set of milling drums having opposing ends and being of a different length        b. each drum in said set of milling drums being divided into segments        c. means for releasably connecting one end of any selected one drum of said set of milling drums to said one end of said housing of the reduction gear        d. a connector element on the other end of at least one of said drums in said set of milling drums whereby said at least one of said drums can be releasably connected at its other end to said drum        
EP1520076 discloses a self-propelled road milling machine comprising a machine chassis, inside of which a milling drum is mounted in such a way to be rotary between side-walls which are orthogonal to the axis of the milling drum, the milling drum, which has a drum base body and a milling pipe, being suitable to be commanded by means of control means that are supported on the exterior of the side-wall on the power intake side and by means of a reduction gear, and the side-wall situated on the opposite side relative to the side-wall on the power intake side, this being easily demountable for changing alternative milling drums, having different milling widths, and defining the zero-side of the machine against which a face of the milling drum is in abutment in an approximately flush way to allow the milling in proximity to a border, characterised in that:                a. the reduction gear is mounted on the intake side of the transmission        b. the reduction gear includes on the exit a transmission element, which is mounted on the inside of the side-wall on the input side of the transmission and whose external surface forms a seat for elements of the milling drum which may be slided on it starting from the zero-side        c. the drum base body is coupled to the reduction gear at the exit free frontal face of the transmission without opposing to the sliding of the elements of the milling drum.        
EP1194651 discloses a milling drum comprising a drum base body driven by a milling drum drive device via a transmission unit, a one-piece tubular milling drum coaxially slidably mounted from one side on the drum base body in a manner allowing exchange thereof, the milling drum carrying cutting tools on the outer surface, the milling drum includes fastening elements radially projecting from an inner surface of the milling drum by which the milling drum can be secured in a rotationally fixed manner to the drum base body, said milling drum drive device being placed in correspondence of a side of said drum base body opposite to said side, said fastening means being provided on at least one side of said milling drum, said milling drum being connected to a side-wall of said drum base body and being radially supported on the other side, said fastening means being connected to the base body including the transmission unit integrated on it, said transmission unit being mounted at the end of the base body with the exit directed towards the control group, the input being controlled by a transmission shaft passing through the base body, said base body being supported by two side-walls of the milling drum housing, said housing being provided with an opening that allows the access to the fixing elements between the milling drum and the control group without dismounting parts of the machine.
DE 10 2004 025567 discloses a device for removing a road surface comprising a chassis, a cutting roller (11), and a cutting roller drive with a transmission. The cutting roller can be exchangeably mounted between the side walls (20) of a cutting roller box and is rotationally driven by the cutting roller drive via the transmission. The cutting roller can be exchanged together with at least one part of one side wall and optionally the transmission as one unit.
EP0694651 though allowing a simplified variation of the milling width of the machine that does not require any replacement of parts related to the transmission, however requires the carrying out of different operations in the changing phase of the milling width, as the milling drum results subdivided into two or more sections, each of the sections able to make the variation of the milling width being divided in segments, each of which, in the illustrated embodiment, covers an arc of 120 degrees. When said sections are not utilized, that is one operates with a reduced milling width, for each of them it is necessary to mount in their respective places a rotating blades wheel suitable to push the milled material toward the collecting belt for facilitating its removal from the inside of the milling drum housing. Said blades wheel is also divided into a number of segments corresponding to the number of segments forming the additional sections of the milling drum and, therefore, in the shown embodiment, three segments each of which covering an arc of 120 degrees. Both the segments of the rotating blades and the segments of the additional sections of the milling drum are screwed by means of bolts on radial protrusions of the transmission shaft. Said bolts are therefore exposed to the milled material, and for this reason at the moment of the change of the milling width it will be necessary to clean the rotating blades and/or the sections of the milling drum to be replaced in order to have access to said bolts, remove all of the bolts of each segment of each section whereon one must intervene, remove the blade segments to replace them with the segments of the milling drum or vice-versa, and screw again the bolts. Said operation requires however a long intervention time because of the need to operate on more then one segment, the intervention times being possibly further increased because of the wear and tear of the bolts caused by the milled material. Moreover the replacement operation of the milling elements occurs accessing the milling drum housing from the back, obliging the operator to work in a narrow space and in uncomfortable working positions. The illustrated preferred embodiment, moreover, provides that the first section, the one defining the minimum milling width, is made in a single piece coaxial to the reduction gear, so that if it is necessary to replace said first section for wearing or damage, it is anyway required the dismounting of the reduction gear itself, with consequent considerable lengthening of the intervention time. Moreover the first milling section, being always in use even in the case of greater milling widths, results subject to a greater wearing compared with the added sections, compromising the quality of the milling itself and requiring a more frequent replacement of the tools of said first section compared with the others. A big problem in this solution is also that when one is working with a milling drum with reduced size compared with the maximum admissible width, the part of the transmission not including the milling sections is rotating inside the milling drum housing containing the milled material, said rotation therefore occurring in the presence of the bituminous milled material that in this way is continuously kneaded contributing to the constitution of agglomerations adhering to said part of transmission and hardly removable. Said rotating action causes also a consisting friction with the milled material present in the milling drum housing that beside worsening the kneading of the material itself, causes a power loss and an early wearing, requiring the presence of replaceable protective elements. Not less important is the presence of a reduction gear different with respect to reduction gears commonly commercially available, because, being said reduction gear mounted at the right-hand side of the machine and symmetrically with respect to the design of the reduction gear mounted at the left-hand side of the machine, it is necessary to use a reduction gear with passing-through hollow input shaft. This entails the following problems:                additional cost due to the need to design a specific reduction gear for this application        additional cost due to the lower number of reduction gears built because they are hardly utilizable in other contexts, where the reduction gears configured with the entry of the transmission shaft according to the conventional design instead find application        problems in supplying spare parts because they are reduction gears of a special embodiment that would therefore require a specific warehouse stock in lower quantities if compared with the stocks of the conventional reduction gears.        
U.S. Pat. No. 5,722,789 presents an embodiment similar to the previous one in which all the sections, including the first one, are subdivided into two opposite segments each of which covering an arc of 180 degrees, rather than three segments, said segments being reciprocally fixed and not on radial protrusions of the transmission shaft. For this reason the transmission of the power to said sections occurs by means of a couple of opposite keys each of them transmitting the motion to the respective corresponding section. These keys are screwed in suitable seats present on the supporting rotating cylinder and are housed in different positions depending on the milling width to be adopted. This solution, though reducing the number of parts to be replaced for each section, requires also the moving of the keys transmitting the motion to said sections, therefore involving anyway a high number of pieces to be replaced. Moreover said solution anyway involves the need to operate on different segments and it also results affected by the problem of the inaccessibility of the fixing bolts both of the keys and of the segment themselves, said bolts being exposed directly to the milled material and therefore requiring a preliminary cleaning operation in order to be able to have access and intervene on them. Moreover the replacement operation of the milling elements occurs accessing the milling drum housing from the back, obliging the operator to work in a narrow space and in uncomfortable working positions. Moreover the first milling section, being always in use, even in the case of greater milling widths, results subject to a greater wearing compared with the added sections, compromising the quality of the milling itself and requiring a more frequent replacement of the tools of said first section compared with the others. Also in this case the problem remains for which when one is working with a milling drum with reduced size compared with the maximum admissible width, the part of the transmission not including the milling sections is rotating inside the milling drum housing containing the milled material, said rotation therefore occurring in the presence of the bituminous milled material that in this way is continuously kneaded contributing to the constitution of agglomerations adhering to said part of transmission and hardly removable. Said rotating action causes also a noteworthy friction with the milled material present in the milling drum housing that beside worsening the kneading of the material itself, causes a power loss and an early wearing, requiring the presence of replaceable protective elements. Also in this case it is necessary the presence of a reduction gear different with respect to reduction gears commonly commercially available, said reduction gear being mounted at the right-hand side of the machine and symmetrically with respect to the usual design, this involving the inversion of the entry of the transmission shaft, that also in this case occurs from the left-hand side of the machine. This entails the aforementioned problems deriving by the additional costs for the need to a specific design of the reduction gear, for the lower number of pieces produced and also deriving by the supplying problems of spare part with respect to conventional reduction gears.
EP1520076 though solving some of the abovementioned problems about the previous solutions, as soon as it uses different milling drums with overall length corresponding to the desired cutting width which can be sideways removed with reference to the machine, has other disadvantages about the positioning of the reduction gear, that is mounted on the left-hand side of the machine involving the presence of an element of transmission able to ensure the possibility to insert the lower width milling drums in such a way that they are flush with the right side of the machine, said element of transmission constituting an additional rotating mass with consistent size. Also in this case the problem remains for which when one is working with a milling drum with reduced size compared with the maximum admissible width, the part of the transmission not including the milling sections, that in this case is the casing of the reduction gear covered with the corresponding protection tube, is rotating inside the milling drum housing containing the milled material, said rotation therefore occurring in the presence of the bituminous milled material that in this way is continuously kneaded contributing to the constitution of agglomerations adhering to said part of transmission and hardly removable. Said rotating action causes also a noteworthy friction with the milled material present in the milling drum housing that beside worsening the kneading effect of the material itself, causes a power loss and an early wearing, requiring the presence of replaceable protective elements.
EP1194651 though solving some of the abovementioned problems about the previous solutions, as soon as it uses different milling drums with overall length corresponding to the desired cutting width which can be sideways removed with reference to the machine, and though having the reduction gear unit mounted on the right side of the machine, has other disadvantages from the point of view of the fixing of the milling drum. In fact, for milling drums with greater width, apart from the fixing point on such element of transmission integral with the reduction gear, an additional support is necessary that in the case of the disclosed invention is realized at the external surface of the base body of the drum itself by means of a movable radial support ring. Said radial support ring can be shifted in various positions depending on appropriate seats realized on the external part of the base body of the drum. If one works with milling drums with lower widths, the seats that are not utilized must be protected from the exposure to the milled material in order to avoid the clogging by means of appropriate protection plates fixed on the seats by means of screws, these screws themselves therefore being exposed to the milled material and subject to clogging due to the same, which lengthens the replacement time of the milling drum when said annular support and said protection plates must be shifted. Also in this case the problem remains for which when one is working with a milling drum with reduced size compared with the maximum admissible width, the part of the transmission not including the milling sections is rotating inside the milling drum housing containing the milled material, said rotation therefore occurring in the presence of the bituminous milled material that in this way is continuously kneaded contributing to the constitution of agglomerations adhering to said part of transmission and hardly removable. Said rotating action causes also a noteworthy friction with the milled material present in the milling drum housing that beside worsening the kneading effect of the material itself, causes a power loss and an early wearing, requiring the presence of replaceable protective elements. Also in this case it is necessary the presence of a reduction gear different with respect to reduction gears commonly commercially available, said reduction gear being mounted at the right-hand side of the machine and symmetrically with respect to the usual design, this involving the inversion of the entry of the transmission shaft, that also in this case occurs from the left-hand side of the machine. This entails the aforementioned problems deriving by the additional costs for the need to a specific design of the reduction gear, for the lower number of pieces produced and also deriving by the supplying problems of spare part with respect to conventional reduction gears.
Therefore, all of the prior art systems, have in common the characteristic that, when milling drums with lower width are mounted, they have at least one part of the transmission system exposed to the milled material present in the case said part being rotating in an integral way together with the milling drum itself. More negative effects are the power loss and the early wearing of the rotating parts dipped in the milled material.
The invention has the following aims:                replace a milling drum of a certain cutting width with a different width drum, without replacing other parts and making this operation fast and easy also for unskilled personal.        replace a milling drum of a certain cutting width with a different or same width drum, but with different spacing of the tools, without replacing other parts and making this operation fast and easy also for unskilled personal.        not penalize the milling depth with respect to the one obtainable with the milling drum with maximum width.        allow the milling “flush to the wall” on the right side of the machine for any width of the milling drum        allow the use of commercially available reduction gears avoiding to recur to reduction gears specifically designed for the application on the machine object of the present invention.        